This is a renewal application to continue work on computer technology for transaxial tomography devices. Attention is to be given to further reducing the required time, cost, and dose for improved reconstructions, especially from data obtained either from rapidly moving objects (heart) or from large amounts of data covering the whole extent of a big organ (lungs), and to the displaying of the results obtained from such data in a truly effective way. This will be done by (i) improvements to an existing programming system and data base, (ii) development of special purpose algorithms for fan-beam and cone-beam geometries, (iii) use of optimization techniques, (iv) minicomputer implementation of an operator-interactive graphics system, and (v) development of special purpose algorithms for reconstruction from incomplete and/or limited view projection data. Continued cooperation with clinical facilities and manufacturers of computerized transaxial tomography equipment will provide immediate medical application of our work. In particular, attention is to be paid to the needs of such state-of-the art developments as (i) the Dynamic Spatial Reconstructor, which is being tested at the Mayo Clinic for the study of cardiopulmonary disabilities, (ii) low dose detection of cancer lesions, (iii) interactive surgical planning, (iv) reconstruction and analysis of the beating heart from echocardiograms, (v) heart-scanning with a hexagonal ring positron camera, and (vi) gated cardiac CT.